Endocannabinoid regulation of behavior in response to negative affective states associated with alcohol abstinence.

Alcohol use disorder (AUD) is characterized by elevated levels of alcohol intake followed by negative affective states when individuals halt alcohol consumption. In individuals suffering from AUD, alcohol taking and seeking is often hypothesized to be motivated by negative reinforcement, where individuals continue consuming alcohol in order to avoid the negative affective states that are triggered by abstinence. Females are particularly vulnerable to the effects of AUD and are more likely to drink to regulate this negative affect produced by abstinence. The endogenous cannabinoid (eCB) signaling system is heavily implicated in the mediation of both reward and reinforcement, and alcohol consumption has been shown to be positively correlated with release of the eCB ligand 2-arachidonoylglycerol (2-AG) within the reward neurocircuitry. Taking this into consideration, we took a multifaceted approach to investigate the mechanisms by which individuals avoid negative affective symptoms associated with prolonged alcohol abstinence, one of the leading causes of relapse. Using a mouse model of chronic alcohol consumption followed by prolonged forced abstinence (CDFA) and pharmacological enhancement of eCB with JZL184, we were able to examine how altered eCB signaling can affect how females respond to avoid negative outcomes. First, by using negative reinforcement operant conditioning, we show that increased eCB signaling via a single injection of JZL184 causes an increase in acquisition rate as compared to ethanol-treated and control animals. After reaching acquisition, a difference in behavioral pattern is noted; when given the chance to either escape or avoid the foot shock, JZL-treated animals consistently chose to escape the shock rather than fully avoid it, possibly indicating a reduced sensitivity to the aversive stimulus. Next, when comparing latency to first bite in the novelty-suppressed feeding test (NSFT), a common protocol used to measure depression and anxiety, with acquisition rate, we found that, in ethanol-treated animals, decreased latency to eat is negatively correlated with days to acquisition. Moreover, we are able to reverse this effect with a single dose of JZL184. Together, these data indicate that a single dose of JZL184 has the ability to cause long-lasting effects on the eCB signaling system and, consequently, the reward circuitry. Moving forward it will be critical to directly link these effects between reinforcement learning and reward processing in order to develop a pharmacological intervention to reduce the negative affective states following alcohol abstinence.